1. Field of the Invention
The invention relates generally to painting machinery and more particularly to a global positioning system (GPS) controlled marker for depositing marks according to GPS-based locations.
2. Description of the Prior Art
Road markings are produced to a great extent with the assistance of so called "road marking" machines which apply paint under pressure from spray nozzle jets onto the road surface. In marking the road it is quite important that the horizontal registration of the paint be accurate with respect to the position of the road. In the past even experienced machine operators have found it difficult to manually guide a road marking machine with sufficient accuracy even where old markings are available. Heretofore, attempts have been made to automatically detect the presence of old markings and to use their detection for automatically guiding the road marking machine and switching the spray nozzle on and off as required. However, such attempts have not been wholly satisfactory because a break in the old marking does not give steering guidance during breaks. Moreover, this approach is of no use whatsoever where the old marks have disappeared or for new markings. Various arrangements have been disclosed for solving these problems by automatically guiding the road marking machine along a pre-determined path using light or electromagnetic beams. However, these arrangements require transmitters to be placed along the road, and in the case of light beams, are degraded by the effect of sunlight. In order to overcome these problems, it has been proposed to embed material that emitting radiation in the path that is to be marked. However, this method suffers from the disadvantage that embedding the radiating material in the road surface can be costly. Furthermore, radiating materials tend to lose their effectiveness after a time period. Similar issues pertain to parking lots, air landing fields, and the like.
For athletic games between teams of individuals it is customary to provide certain markings with chalk, lime, or paint of the various portions of the field on which the game is played. It is common for teams to add drawings for their logos or for advertisers to add picture-like patterns to the fields. Athletics such as American football, soccer, rugby, and baseball, are held on the same field at different times but require different sideline markings as well as different markings within the playing field. Even athletic fields dedicated to one sport need to be re-surveyed and re-marked at intervals. Commonly, a tape measure and a rule book are used for marking such fields. However, this method can be inconvenient and time consuming and the accuracy of the markings will vary from time to time. In order to improve upon this method, many fields have installed permanent pegs or upright markers securely anchored to the ground in surveyed locations that can be used for sighting. However, the large number of markers and pegs for several different game markings can give the field a confused appearance and be hazardous. Furthermore, the uprights and pegs are of limited use for marking team logos or advertisements. The appearance can be improved and the hazard reduced by using removable uprights where only the anchor remains in place, however, this is of no benefit for picture-like patterns.
There is a need for a system for automating the marking of roads and fields that does not require light or electromagnetic beams, embedded materials, or upright sighting markers that is capable of marking lines and picture-like patterns.